21012222001 has 4 divisors (see below), whose sum is σ = 21067663600. Its totient is φ = 20956780404.

The previous prime is 21012221981. The next prime is 21012222017. The reversal of 21012222001 is 10022221012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21012222001 - 2²⁵ = 20978667569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21012222901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27720231 + ... + 27720988.

It is an arithmetic number, because the mean of its divisors is an integer number (5266915900).

Almost surely, 2^21012222001 is an apocalyptic number.

It is an amenable number.

21012222001 is a deficient number, since it is larger than the sum of its proper divisors (55441599).

21012222001 is an equidigital number, since it uses as much as digits as its factorization.

21012222001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55441598.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 21012222001 its reverse (10022221012), we get a palindrome (31034443013).

The spelling of 21012222001 in words is "twenty-one billion, twelve million, two hundred twenty-two thousand, one".